1. Field of the Invention
This invention relates to a golf ball comprising a solid core, an intermediate layer, and a cover, and more particularly, such a golf ball wherein the cover is formed of a specific diamine complex ionomer resin so that the ball is improved in flight performance, hitting feel and durability.
2. Prior Art
Various types of golf balls are available in the market. The majority of the ball market is shared by two-piece solid golf balls in which a rubber base core is enclosed with a cover of ionomer resin or the like and wound golf balls in which a wound core having thread rubber wound on a solid or liquid center is enclosed with a cover.
Most average golfers favor two-piece solid golf balls because of superior flight performance and durability. The two-piece solid golf balls, however, have the drawback that hitting feel is hard and controllability is low because of quick separation of the ball from the club head. Thus many professional golfers and low-handicap players prefer wound golf balls to two-piece solid golf balls. The wound golf balls are superior in feel and control, but inferior to two-piece solid golf balls in flight distance and durability.
Under the present situation that two-piece solid golf balls and wound golf balls have contradictory characteristics as mentioned above, players make a choice of golf balls depending on their own skill and preference.
In order to develop solid golf balls having a feel approximate to the wound golf balls, various two-piece solid golf balls of the soft type have been proposed. To obtain such two-piece solid golf balls of the soft type, soft cores are used. Softening the core can reduce resilience, deteriorate flight performance, and substantially lower durability, resulting in two-piece solid golf balls which not only fail to possess their characteristic excellent flight performance and durability, but also lose actual playability. Differently stated, while the structure of conventional two-piece solid golf balls is determined by the desire to optimize three factors, softness, resilience and durability, an attempt to improve one of these factors tends to sacrifice the remaining factors.
To solve the above-mentioned problem, JP-A 24084/1995 proposes a golf ball comprising a core, an intermediate layer surrounding the core, and a cover surrounding the intermediate layer. In order that the ball of this structure exert its performance to a full extent, it is desired to further improve the materials used therein. There is a need for further research work to improve the golf ball having an intermediate layer between a core and a cover.